Biophysics Unit, Department of Biochemistry and Molecular Biology, School of Medicine, and Center for Biophysical Studies, Universitat Autonoma de Barcelona, 08193 Bellaterra, Catalonia, Spain.
J Biol Chem. 2011 Jan 28;286(4):2486-91. doi: 10.1074/jbc.M110.190843. Epub 2010 Nov 23.
An intra-S phase checkpoint slows the rate of DNA replication in response to DNA damage and replication fork blocks in eukaryotic cells. In the budding yeast Saccharomyces cerevisiae, such down-regulation is achieved through the Rad53 kinase-dependent block of origins of replication. We have identified the Rad53 phosphorylation sites on Dbf4, the activator subunit of the essential S phase Dbf4-dependent kinase, and generated a non-phosphorylatable Dbf4 mutant (dbf4(7A)). We show here that dbf4(7A) is a bona fide intra-S phase checkpoint bypass allele that contributes to abrogating the Rad53 block of origin firing in response to genotoxic stress.
在真核细胞中，一个 S 期内检验点通过减缓 DNA 复制的速度来响应 DNA 损伤和复制叉阻塞。在芽殖酵母酿酒酵母中，这种下调是通过 Rad53 激酶依赖性阻止复制起点来实现的。我们已经确定了必需的 S 期 Dbf4 依赖性激酶的激活亚基 Dbf4 的 Rad53 磷酸化位点，并生成了一个非磷酸化的 Dbf4 突变体（dbf4(7A)）。我们在这里表明，dbf4(7A) 是一个真正的 S 期内检验点旁路等位基因，有助于消除遗传毒性应激下 Rad53 对起源点火的阻断。
